1. Field of the Invention
The invention is in the field of solar energy conversion apparatus for converting solar energy directly into electrical energy.
2. Description of the Prior Art
Prior art solar energy conversion systems utilized to directly produce electrical energy employ semiconductor material which, upon exposure to solar radiation produces electron-hole pairs and a corresponding electric current when a potential is applied across the semiconductor surfaces. Examples of such prior art devices are taught in U.S. Pat. Nos. 2,736,848, 2,981,777 and 2,949,498. Alternate prior art devices employ photoemissive surfaces which, upon exposure to incident solar radiation liberate electrons by means of the photoelectric effect. Typically, the liberated electrons are collected through a vacuum space on a collecting surface and the potential produced between the emitting and collecting surfaces form a voltage source which may be utilized for driving a load. Examples of such teachings are shown in U.S. Pat. Nos. 3,121,648 and 3,218,196. A similar technique utilizes thermally liberated electrons from an emitting surface upon exposure to incident solar radiation. The thermally liberated electrons are collected on a collecting plate and utilizes to drive a load. U.S. Pat. No. 3,026,439 is an example of such a thermal energy converter.
The prime disadvantage of the prior art direct conversion systems is in their low efficiency and high cost. Typically, such devices may find application in various trigger circuits such as door openers, alarm detectors and the like but do not find broad application as prime energy sources per se.